1. Field of the Invention
The present invention relates to laser pointers. More particularly, the present invention relates to hand-held laser pointers. Even more particularly, the present invention relates to a hand-held laser pointer stabilized against hand tremor.
2. Prior Art
Various hand-held laser pointers have been taught for visually pointing out a target on, for example, a whiteboard, chart, map, or projected display. Laser pointers typically include a laser diode module that produces a collimated laser beam. The laser diode module is packaged within a housing and is battery powered. A user holds the pointer in one hand and directs the laser beam towards a target, generally during a presentation or the like.
The effectiveness of such hand-held laser pointers for particularly pointing out a target is reduced by the unintentional tremor of the user's hand. Human tremor is an involuntary trembling or shaking of the muscles of the body associated with physical weakness, emotional stress, or excitement. The small angular movements of the hand from tremor impart undesirable motion to the laser pointer and its corresponding laser beam and image, which is generally a small dot indicating where the beam is striking the target. This unwanted motion is amplified as the distance between the laser diode and the target increases and generally results in visibly shaky movements of the laser dot. The jitter of the laser dot limits the user's pointing resolution which may distract an audience, expose nervousness and may act to discredit the user.
To address this problem, some hand-held laser pointer devices have been taught that blink on and off, or create a pulsed laser beam. These devices mask the problem and do not stabilize the orientation of the laser light beam. Uninterrupted siting of the laser dot is additionally not achieved by this type of laser pointer.
Other suggested means for coping with hand tremor while pointing a hand-held laser pointer include turning the laser on only momentarily, holding the pointer with both hands to reduce tremor, resting the pointing hand, wrist, or arm on a stable object, or connecting the pointing device directly to a stable object such as a podium. The lack of an adequate solution to this problem has prompted many to suggest that hand-held laser pointers should not be used during presentations.
Artisans have made attempts to provide a laser pointer wherein the pointer is protected from damage when subjected to high frequency vibration and shock. For example, LaCroix, in U.S. Pat. No. 4,357,649, disclosed a laser pointer wherein the laser is protected from shock by supporting it with a cushion material at each end within its housing. It can be shown mathematically that the construction disclosed by LaCroix is inoperable for isolating the laser from low-frequency tremor as occurs when hand-held. The required natural frequency of the suspended laser must be significantly lower than the frequency of hand tremor. Hand tremor is small in magnitude and slow in frequency, less than 0.1 degree at 4 Hz frequency. A cushion means to support the laser transmits the majority of the unwanted low frequency hand tremor motions of the housing to the laser.
Artisans have disclosed laser devices that point in a direction relative to the direction of gravity irrespective of the housing orientation. WU, in U.S. Pat. No. 6,035,540, teaches an industrial laser level using a hanging mechanism. The invention of WU requires that the pivot for the laser be significantly offset from the center of mass of the counterweighted pivoting assembly in order that the laser always points in the direction of gravity. The invention of WU continues pointing in a direction relative to the direction of gravity when the housing is tilted. NG, in U.S. Pat. No. 6,792,685, teaches a damped bearing assembly for a laser plumb that includes a spinning mass affixed to the pivoting laser assembly. Similar to WU, NG's invention only points in a direction relative to the direction of the gravity and is structurally designed for that purpose. The inventions taught by WU and NG are not sufficient to enable a laser to be both arbitrarily aimed in an arbitrary desired direction by pointing the housing while at the same time attenuating motions due to hand tremor.
There is a need in the art for an improved hand-held laser pointer that substantially eliminates the effect of hand tremor on the direction of the laser beam produced by a hand-held laser pointer.